Cannabis sativa L. is one of the world’s most recognizable plants, from both a visual and aromatic perspective. It is also an extremely useful plant. While much of the popular focus is on the use of cannabis as an illicit “drug,” this is only one of the many diverse uses of cannabis. Most famously, the flowers contain many compounds of pharmaceutical interest, both therapeutic and recreational. They are also rich in terpenoids notable for their flavor and aroma. The seeds are very nutritious and can also be used for oil production, while the leaves are edible as leafy greens or for decoction (tea). The stalks are an excellent source of fiber for textiles, paper and rope. The roots are also used for decoctions and have a long history of therapeutic use.
Given this remarkable utility, it is hardly surprising that humans have been using cannabis in various ways for millennia. Domestication is postulated to have begun on the Central Asian steppes as many as 12,000 years ago, and burned cannabis seeds were found in Siberia in 5,000-year-old kurgan burial mounds of the Pazaryk tribes. A large cache of cannabis found in the 2,700-year-old grave of a Caucasoid shaman in Xinjiang contained tetrahydrocannabinol (THC). This is the oldest physical proof of THC use.
There is a long-running debate among botanists over whether fiber (hemp) and drug (marijuana) cultivars are subspecies of a single species or should be divided into two closely related species — the tall, fibrous C. sativa and the shorter, more intoxicating C. indica. It is important to note that this does not correlate to the sativa/indica terminology used in the marketing of drug cultivars, all of which would fall under C. indica. In this article, the monotypic (single species) classification of Cannabis is used because it is more common in the scientific literature than the polytypic one. Thus, the two are referred to here as C. sativa L. subsp. sativa and C. sativa L. subsp. indica.
Use of cannabis to flavor or enhance a beverage will generally be through infusion or distillation — or a combination thereof. As with any botanical used in such methods, it is useful to consider the flavor, solubility, volatility and stability of the key compounds targeted for incorporation into the beverage.
Flowers
The rich and diverse terpenoid content of the flowers makes them a logical choice for a flavoring agent in a wide variety of applications, including beverages. Cannabis flowers can exhibit a broad array of aromas, so cultivar and growing conditions, in addition to extraction methods, have a major impact on their flavor contribution. Unfertilized flowers (aka sinsemilla or ganja) contain much more cannabinoids than fertilized ones. Cannabis is a close cousin of Humulus lupulus (hops), and the flowers will behave in a similar manner to aromatic hops in both infusion and distillation. If distilling at atmospheric pressure or low vacuum, a long maceration will substantially improve the extraction. Avoiding mechanical damage to the flowers until immediately prior to use will help to preserve the aroma. Plants contaminated with pesticide or nutrient residues should always be avoided.
Leaves and Stems
The leaves and stems of cannabis typically impart green, herbaceous, menthol notes with a subtle echo of the terpenoid profile of the flowers. When infused, the leaves provide a pleasant grassy sweetness, while the stems are typically more vegetal, reminiscent of spinach. Both contribute tannic elements as well, though the stalks are much woodier. Like the flowers, both also imbue the infusion with an attractive green hue. If distilling at atmospheric pressure or low vacuum, special care should be taken not to acquire a cooked greens aroma. Unless this is a desired note in the product, any distillate with this characteristic should be diverted to feints, as it is quite insidious.
Seeds
Cannabis seeds are rich in lipids and proteins. As such, infusions tend to be oily, hazy and even milky. In general, they are better suited to distillation. When distilled, raw, shelled seeds give mild waxy and creamy notes. Dry-toasted seeds in the shell contribute a much greater depth of flavor — nutty, earthy and slightly savory. Seeds with added oil or salt should be avoided.
Roots
Cannabis roots are often overlooked and discarded, but they have tremendous potential in infusions. Raw, they can provide an earthy, musty, savory bitterness reminiscent of reishi mushrooms (also rich in triterpenoids). Sometimes, they are less bitter and closer in flavor to chanterelles, and they can even contribute rustic spice and mint notes. The roots can also be roasted to enhance the bitterness and pungency and introduce a nutty note. Depending on the level of roasting, they can be reminiscent of roast chicory or dandelion roots and make an excellent bittering agent. Due to the very low volatility of many of the compounds of interest, the roots are better suited to infusion than distillation.
Cannabinoids
Over 150 cannabinoids have been described in C. sativa. Cannabinoids produced by cannabis (phytocannabinoids) are chemically distinct from those produced by the human body (endocannabinoids) but interact with many of the same receptors in the endocannabinoid system. As such, cannabinoids are the most pharmacologically active compounds in cannabis, but will not contribute to the flavor of a beverage. Cannabis flowers contain the overwhelming majority of cannabinoids present in the plant, with only trace amounts found in the stems and leaves, and none in the roots. The unfertilized flowers of some modern chemovars can contain over 30% cannabinoids by dry mass. C. sativa L. subsp. indica is generally THC dominant, though a few chemovars contain a roughly equal balance between cannabidiol (CBD) and THC, while C. sativa L. subsp. sativa is CBD dominant. THC produces intoxicating and euphoric effects and has also been shown to impact pain, spasticity, sedation, appetite and mood. CBD appears to have anticonvulsive, anti-inflammatory, antioxidant and antipsychotic effects, though more research is needed. It should be noted, however, that these effects are generally observed with doses one or two orders of magnitude greater than that of the beverages typically available, which is 5–25 mg per serving. Even at low concentrations, CBD can modulate the high of THC through its ability to antagonize the CB1 receptor in the presence of THC. Another cannabinoid of note is cannabinol (CBN). This cannabinoid is produced by the nonenzymatic degradation of THC and is often indicative of old, poorly stored and/or poorly processed cannabis.
When seeking to incorporate cannabinoids into a beverage or other product, it is crucial to understand decarboxylation. This refers to the replacement of a carboxylic acid group (COOH) with a hydrogen (H), and corresponding release of CO2. THC and CBD do not actually occur in significant quantities in fresh cannabis. Rather, their corresponding acids (THCA and CBDA) predominate, but do not share the same pharmacological properties as their neutral counterparts. These acids are not thermally stable and are decarboxylated when exposed to heat, such as in smoking, vaping or baking. While decarboxylation occurs faster at higher temperatures, higher is not necessarily better. Higher temperatures will result in the evaporation and degradation of volatile and thermally unstable compounds such as monoterpenoids (see next section) or the conversion of THC to CBN. In experiments conducted by Wang, et al. (2016), complete decarboxylation of THCA and CBDA was achieved within 40 minutes when baked at 110° C (230° F), though some of the target cannabinoids were lost. Losses were greater at higher temperatures. At lower temperatures, significant acidic fractions remained after 60 minutes (incomplete decarboxylation). (See Table 1, right.)
Cannabinoids are nonpolar (hydrophobic) compounds, as are lipids. Water, by contrast, is a very polar (hydrophilic) molecule. This is why cannabinoids are soluble in lipids, such as oils and fats, but insoluble in water. It is possible to form an emulsion of these compounds in water, but it will be unstable without the addition of a stabilizing emulsifier. Happily, aqueous ethanol is an alternative solution in both meanings of the word. Ethanol is an amphipathic molecule, meaning it has both nonpolar and polar regions. Simply put, it is thus able to act as a solvent for the nonpolar cannabinoids, and it is also completely miscible with water. Most alcoholic beverages, particularly spirits and macerations, are dependent to some extent on this property of ethanol in order to maintain their full complement of flavor compounds in solution. This is why some spirits, such as absinthe, turn cloudy when diluted.
The boiling point of THC and other cannabinoids is surprisingly unclear. The most common figure for THC is 157° C at 760 mm Hg (atmospheric pressure). However, this seems oddly low and is contradicted by data published by the World Health Organization (2018) and the U.S. National Library of Medicine (2019), which both list it as 200° C at 0.02 mm Hg (medium vacuum). Either way, the boiling point (a proxy for volatility) of most cannabinoids is significantly higher than that of ethanol (78° C/172° F) or water (100° C/212° F), so distillation at atmospheric pressure would be ineffective. They can be extracted via distillation under medium to high vacuum, but their low volatility will cause them to congregate with other low volatility compounds if employed as a botanical, potentially complicating a tails cut if trying to incorporate them into the spirit. (See Table 2, above.)
Terpenoids
Terpenoids are responsible not only for the key aromas of cannabis, but of most flowers, herbs and spices. They comprise the vast majority of essential oils. Cannabis flowers can contain over 3.5% terpenoids by dry mass. They are also found in much lower quantities in the rest of the plant. Although as many as 200 cannabis terpenoids have been described, there are approximately 50 that are routinely encountered in North American chemovars. These are primarily monoterpenoids (10 carbons) along with some sesquiterpenoids (15 carbons), none of which are unique to cannabis. With the notable exceptions of carvone and dihydrocarvone, the roots do not contain significant mono- or sesquiterpenoids, but they do contain heavier triterpenoids (30 carbons). Recent research indicates that terpenoids might not only be involved in the aroma of cannabis, but might be pharmacologically active themselves, helping to modulate and tune the effects of cannabinoids such as THC.
Terpenoids are nonpolar. The solubility and extraction of terpenoids is similar to that of cannabinoids (see previous section). As shown in the table below, they exhibit a range of boiling points, but all are above that of water. When distilling, it is important to remember the implications of Dalton’s and Raoult’s laws — compounds in the still will vaporize below their boiling points, proportional to their concentration and volatility. Therefore, even at atmospheric pressure, a portion of terpenoids will make it through the still. Because these compounds tend to have very low flavor threshold values, they can still have a major impact on the spirit at very low concentrations. However, the use of a vacuum still greatly improves recovery, and the lower operating temperature prevents thermal degradation. (See Table 3, above.)
Cannabis also contains chlorophyll and flavonoids, with the content being highest in the leaves. The former will not be extracted well in water but is ethanol soluble. It is the pigment responsible for the green coloration of most photosynthetic plants, so will convey this property to a beverage. It also has a flavor that is best described as “green,” with herbaceous, minty undertones. Flavonoids (aromatic, polycyclic phenols) vary in their water solubility, but they will generally extract well in aqueous ethanol. Approximately 20 flavonoids have been identified in cannabis and some have anti-inflammatory, antioxidant and analgesic properties. Cannabis flavonoids primarily contribute herbaceous bitter notes as well as a mild tannic mouthfeel. Many flavonoids are pigments used by plants for yellow, red and blue, so will also impact the color of a beverage. For example, the purple coloration seen in some cannabis cultivars is due to classes of flavonoids called anthocyanidins and anthocyanins. Chlorophyll is not volatile, so will not be extracted through distillation. Cannabis flavonoids exhibit a variety of boiling points, and it is possible to extract a few of them under vacuum distillation, but most have very low volatilities. Many will degrade during sustained boils at atmospheric pressure, though the products of this degradation will often be pigmented as well. The level of degradation is heavily dependent on the exact compound in question. (See Table 4, above.)
Conclusion
Despite the convoluted bureaucratic regulations and politics of cannabis, it is an extremely versatile plant with a long history and tremendous potential for beverage applications. Future articles will focus on detailed techniques for using the various parts of the plant, incorporating empirical data from trials as well as historical sources.
Suggested Further Reading
General Textbook — Small, E. (2013). Cannabis: A Complete Guide. Boca Raton: CRC Press.
History and Ethnobotany — Clarke, R., and Merlin, M. (2016). Cannabis: Evolution and Ethnobotany. Berkeley: University of California Press.
Pharmacology and Terpenoids — Russo, E. B., and Marcu, J. (2017). Cannabis Pharmacology: The Usual Suspects and a Few Promising Leads. Advances in Pharmacology, 80, 67–134. doi:10.1016/bs.apha.2017.03.004
